Developing agent precursors

ABSTRACT

ESTERS OF AMINO REDUCTONES OFFER IMPROVED SOLUBILITY OVER THE PARENT REDUCTONES IN AQUEOUS OR MILDLY ALKALINE SOLUTIONS, IMPROVED STABILITY WHEN PROVIDED AS INCORPORATED DEVELOPING AGENT PRECURSORS IN SILVER HALIDE PHOTOGRAPHIC ELEMENTS, AND ARE ALSO USEFUL AS ANTIOXIDANTS AND ANTI-STAIN AGENTS. THESE ESTERS OF AMINO REDUCTONES, SUCH AS PIPERIDINO HEXOSE REDUCTONE MONOACETATE, ARE USEFUL PHOTOGRAPHIC SILVER HALIDE DEVELOPING AGENT PRECURSORS. THEY CAN BE EMPLOYED IN PHOTOGRAPHIC COMPOSITIONS, ELEMENTS AND/OR PROCESSING COMPOSITIONS.

United States Patent Oflice 3,700,442 Patented Oct. 24, 1972 3,700,442 DEVELOPING AGENT PRECURSORS Rolf S. Gabrielsen and Ismael A. Olivares, Rochester,

N.Y., assignors to Eastman Kodak Company, Rochester, N.Y. No Drawing. Filed Nov. 2, 1970, Ser. No. 86,315

Int. Cl. C03c 5/54 US. Cl. 96-29 20 Claims ABSTRACT OF THE DISCLOSURE Esters of amino reductones offer improved solubility over the parent reductones in aqueous or mildly alkaline solutions, improved stability when provided as incorporated developing agent precursors in silver halide photographic elements, and are also useful as antioxidants and anti-stain agents. These esters of amino reductones, such as piperidino hexose reductone monoacetate, are useful photographic silver halide developing agent precursors. They can be employed in photographic compositions, elements and/or processing compositions.

BACKGROUND OF THE INVENTION Field of the invention The present invention relates to photographic materials and to a method of photographic development. More particularly, the present invention relates to photographic materials containing esters of amino reductones and to a method of processing and using the same.

Description of the state of the art Photographic materials in which a developing agent is incorporated into the silver halide emulsion layer or into a layer adjacent thereto, and which is activated and released by alkaline treatment of the layers after exposure, are well known in the art. However, a dilfficulty often encountered with the incorporation of developing agents in photographic emulsions is the problem of premature reaction of the incorporated developing agent with the .silver halide grains in the emulsion. Developing agent precursors designed to overcome this deficiency have been described. For example, US. Pat. 3,236,988 of Porter and Gompf, issued Apr. 19, 1966, describes esterified hydroquinones such as 1,4-bis (chloroacetoxy)benzene. Cyclized esters have also been described, such as the catechol carbonates described in German application 1,180,245. However, these modified developing agents are much less soluble in aqueous solution or mild alkali than the parent hydroxy developing agents.

The use of various reductones as photographic developers and for other purposes in photographic materials has been described in US. Pat. 2,691,589 of Henn et al., is-

sued Oct. 12, 1943; U.S. Pat. 2,806,794 of Hodge, issued Sept. 17, 1957; US. Pat. 2,936,308 of Hodge, issued May 10, 1960; US. Pat. 3,301,678 of Humphlett et al., issued Ian. 31, 1967; and U8. Pat. 3,347,671 of Salminen, issued Oct. 17, 1967. The amino hexose reductones and their anhydro and dihydro anhydro derivatives have been of particular interest. It has been proposed to employ these latter compounds as developing agents in aqueous solution for conventional photographic processing and/or incorporate them in emulsions. However, their solubility is frequently insufficient to allow easy solution in developer compositions or incorporation in emulsions, receivers and the like.

Accordingly, there has been a continuing need to provide reductone developing agent precursors, antioxidants, and anti-stain agents having greater solubility than related prior art reductone compounds without providing undesired sensitometric characteristics. Another object is to provide reductones having greater stability when present as incorporated developing agent precursors in photographic silver halide compositions and elements.

SUMMARY OF THE INVENTION According to the invention, it has been found that esters of amino reductones surprisingly exhibit increased solubility in water and mildly alkaline solutions compared to unesterified amino reductones. This increased solubility permits the amino reductone esters of the invention to be more easily employed as developing agent precursors, antioxidants, and anti-stain agents than heretofore possible with reductone developing agents. In addition, the amino reductone esters of the invention have greater stability in photographic elements.

According to the invention, it has been found that in photographic elements, compositions and processes an amino reductone ester silver halide developing agent precursor provides improved solubility characteristics, as described, without loss of desired sensitometric characteristics are provided.

DETAILED DESCRIPTION OF THE INVENTION A range of amino reductone ester silver halide developing agent precursors can be employed according to the invention.

They include amino reductone esters of the formula:

Ra Ra wherein R and R are each hydrogen, alkyl, especially alkyl containing 1 to 20 carbon atoms, such as methyl, ethyl, propyl, butyl, pentyl and eicosyl, or atoms which with the nitrogen atom complete a saturated heterocyclic ring, such as 5 or 6 member heterocyclic ring, e.g., morpholino, pyrrolidino, piperidino, and methylpiperazino; R is acyl, especially acyl containing lto 5 carbon atoms, 1.e.,

or -SO R.,, wherein R is alkyl containing 1 to 20 carbon atoms, preferably alkyl containing 1 to 6 carbon atoms, such as methyl, ethyl, propyl, butyl, pentyl or hexyl, aryl, especially aryl containing 6 to 12 carbon atoms, e.g., phenyl, tolyl or xylyl, amino, or a heterocyclic group, e.g., a 5 or 6 member heterocyclic group, such as morpholino, pyrrolidino, piperidino, and methyl piperazino; n is a positive integer of 1 to 2; R and R are each hydrogen, hydroxy, or alkyl containing 1 to 5 carbon atoms, e.g., methyl, ethyl, propyl, butyl or pentyl.

Suitable compounds of the invention include esters of amino hexose reductones, esters of anhydro amino hexose reductones, esters of anhydro dihydro amino hexose reductones, esters of amino hydroxy cyclopentonones and esters of amino hydroxy cyclohexenones. These include,

dimethylamino, diallylamino, di-n-butylamino, di-n-hexylamino, morpholino, i-methyl piperazino, pyrrolidino,

piperidino, dimethylmorpholino, methyl piperidino, or N-benzyl-N-methylamino.

The described anhydro dihydro reductone compounds, are typically prepared from the corresponding anhydro hexose reductone compounds which in turn are prepared from corresponding amino hexose reductones. These compounds are then employed in preparing the described esters. A typical method of preparing the described amino hexose reductones and anhydro amino hexose reductions is set out in U.S. Pat. 2,936,308 of Hodge issued May 10, 1960. Such compounds are typically prepared from sugars, especially D-glucose, although other reducing sugars such as D-galactose, D-fructose, L-sorbose or the like can be used. A typical method of preparing the starting amino hexose reductones consists of heating in a reaction medium, substantially free of water, a reducing sugar, as described, and an aliphatic or cyclic secondary amine in the presence of an acidic reductone-forming catalytic agent such as phosphoric acid, boric acid, acetic acid, succinic acid or the like. The removal of 3 moles of water results during the formation of the amino hexose reductone. The described anhydro amino hexose reductone can be prepared by heating the hydrochloride salts of the amino hexose reductone further in the presence of strong acids such as sulfuric acid, acetic ahnydride, zinc chloride and the like, to remove another mole of water. The described anhydro dihydro hexose reductone compounds can be prepared from the corresponding anhydro amino reductones by hydrogenation in the presence of a suitable hydrogenation catalyst such as Raney nickel catalyst. The preparation of anhydro dihydro piperidino hexose reductone is typical of the preparation of the class of compounds which can be employed in preparation of the described esters of the invention. One mole of anhy drous D-glucose and 1.3 moles of piperidine are stirred together in absolute ethanol under nitrogen for about minutes. The resulting mixture is then heated on a steam bath and stirred until the solution becomes homogeneous. Then a solution of glacial acetic acid in absolute ethanol is added dropwise to the solution. The resulting solution is stirred and refluxed under nitrogen for about 12 hours. It is then cooled and the crystals which are formed are filtered, washed and recrystallized, such as from ethanol. The resulting piperidino hexose reductone is treated with a butanol solution of anhydrous hydrogen chloride to form the intermediate anhydro piperidino hexose reductone. This product is then hydrogenated in ethanol over a suitable catalyst, such as Raney nickel, to form the desired anhydro dihydro piperidino hexose reductone. The resulting product can be purified if desired such as by recrystallization from a suitable solvent such as ethanol. The procedure for preparation of an anhydro dihydro amino hexose reductone is set out in Tetrahedron, volume 6, pages 123-138 (1959).

The described esters of the invention are then prepared by esterification of the corresponding amino compound, as by heating together the amino compound and an organic acid, an anhydride, or halide in the presence of a suitable solvent. A basic condensation catalyst, such as trimethyl-am-ine or tripropylamine is usually employed to aid the reaction. As a specific example, a preferred compound, piperidino hexose reductone monoacetate, which is represented by the formula:

HOACHJ ing the excess acetic anhydride by low pressure distillation. A suitable solvent can be employed if desired.

The described silver halide developing agent precursors can be employed in the practice of the invention in the form of a salt, especially an acid salt such as a hydrochloride, sulfate or the like salt. A silver halide developing agent precursor as described herein includes such compounds either in salt form or in their nonsalt form.

The described silver halide developing agent precursors can be employed in combination with any silver halide developing agent or developing agent precursor. The developing agents can be employed in such combinations as auxiliary developing agents or as the main component of the developing combination. Suitable silver halide developing agents which can be employed include, for example, polyhydroxybenzene, such as hydroquinone silver halide developing agents, e.g. hydroquinone, alkyl-substituted hydroquinones as exemplified by tertiary butyl hydroquinone, methyl hydroquinone, 2,5-dimethyl hydroquinone and 2,6-dimethyl hydroquinone; catechols and pyrogallols; chloro-substituted hydroquinones, such as chlorohydroquinone or dichlorohydroquinone; alkoxysubstituted hydroquinone such as methoxy hydroquinone or ethoxy hydroquinone; aminophenol developing agents, such as 2,4-diaminophenols and methylaminophenols; ascorbic acid developing agents such as ascorbic acid, ascorbic acid ketals and ascorbic acid derivatives, such as those described in U.S. Pat. 3,337,342 of Green issued Aug. 22, 1967; hydroxylamine developing agents such as N,N-di(Z-ethoxyethyl)hydroxylamine; 3-pyrazolidone developing agents such as l-phenyl-3-pyrazolidone and 4 methyl-4-hydroxymethyl-1-phenyl-3-pyrazolidone, and acyl derivatives of paraaminophenol such as described in British Pat. 1,045,303 published Oct. 12, 1966 and the like. Combinations of these developing agents can be employed, if desired.

One embodiment of the invention is a photographic element comprising a support, photographic silver halide, and an amino reductone ester silver halide developing agent precursor, as described.

In general, the described silver halide developing agent precursors can be in any suitable location in and/or on a photographic element as described. For example, the silver halide developing agent precursor and/or a silver halide stabilizer precursor can be in a photographic silver halide emulsion layer, typically a silver halide gelatino emulsion layer, and/or in a layer which is contiguous to a photographic silver halide layer. They can be incorporated into a hydrophilic colloid layer, especially a gelatin layer, which is over a photographic silver halide layer and farther from the support than a silver halide layer and/ or they can be incorporated into a layer which is between a photographic silver halide layer and the support.

A range of concentration of silver halide developing agent precursor, as described, can be employed in the practice of the invention. Typically the concentration of silver halide developing agent precursor is about 1 mole to about 10 moles per mole of silver present in the photographic element, preferably about 15 moles to about 4 moles of silver halide developing agent precursor per mole of silver. This usually corresponds to about 10 to about 500 milligrams of silver halide developing agent precursor per 929 square centimeters of support, preferably about 20 to about milligrams of developing agent precursor per 929 square centimeters of support.

The silver halide emulsions which can be employed with this invention can be silver chloride, silver bromide, silver bromoiodide, silver chlorobromoiodide or mixtures thereof. The emulsions can be coarse or fine-grain and can be prepared by any of the well-known procedures in emulsion making such as single-jet emulsions, double-jet emulsions, such as Lippmann, ammoniacal emulsions, thiocyanate or thioether ripened emulsions, such as those described in U.S. Pat. 2,222,264 of Nietz et a1. issued Nov. 4, 1940; U.S. Pat. 3,320,069 of Illingsworth issued May 15, 1967 and U.S. Pat. 3,271,157 of McBride issued Sept. 6, 1966. Surface image emulsions can be used or internal image emulsions such as those described in U.S. Pat. 2,592,250 of Davey et al. issued Apr. 8, 1952; U.S. Pat. 3,206,313 of Porter et al. issued Sept. 14, 1965; U.S. Pat. 3,367,778 of Berriman et al. issued Feb. 6, 1968; and Belgian Pat. 704,255. If desired, mixtures of surface and internal image emulsions can be used as described in U.S. Pat. 2,996,382 of Luckey et al. issued Aug. 15, 1961. Negative type emulsions can be used or direct positive emulsions such as those described in U.S. Pat. 2,184,013 of Leermakers issued Dec. 19, 1939; U.S. Pat. 2,541,472 of Kendall et al. issued Feb. 13, 1951; U.S. Pat. 3,367,778

of Berriman et al. issued Feb. 6, 1968; British Pat. 723,- v

019; French Pat. 1,520,821; U.S. Pat. 2,563,785 of Ives issued Aug. 7, 1951; U.S. Pat. 2,456,953 of Knott et al. issued Dec. 21, 1958 and U.S. Pat. 2,861,885 of Land issued Nov. 25, 195 8. The emulsions can be regular grain emulsions such as those described in Klein and Moisar, Journal of Photographic Science, volume 12, No. 5, September-October 1964, pages 242-251.

The silver halide emulsions employed in the practice of the invention can be unwashed or washed to remove soluble salts- In the latter case the soluble salts can be removed by chill-setting and leaching or the emulsion can be coagulation washed. t

The silver halide emulsions employed in the practice of the invention can be sensitized with chemical sensitizers, such as with reducing agents; silver, selenium, or

such as polyalkylene glycols, cationic surfactants and thioethers or combinations of these as described, for example, in U.S. Pat. 2,886,437'of Piper issued May 12, 1959; U.S. Pat. 3,046,134 of Dann et al. issued July 24, 1962; U.S. Pat. 2,944,900 of Carroll et al. issued July 12, 1960 and U.S. Pat. 3,294,540 of Goffe issued Dec. 27, 1966.

The described silver halide emulsions employed in the practice of the invention can be protected against the production of fog and can be stabilized against loss of sensitivity during keeping. Suitable antifoggantsand stabilizers each-used alone or in" combination include, for example, thiazolium salts; azaindenes, mercury salts as described, for example, in U.S. Pat. 2,728,663 of Allen et al. issued Dec. 27, 1955; urazoles; sulfocatechols; oximes described, for example, in British Pat. 623,448; nitron; nitroindazoles; mercaptotetr'azoles; polyvalent metal salts described, for example, in U.S.'Pat. 2,839,405 of Jones issued June 17, 1958'; palladium, platinum and gold salts described, for example, in U.S. Pat. 2,566,263 of Trevelli et al. issued Aug. 28, 1951 and U.S. Pat. 2,597,915 of Yutzy'et al. issued May 27, 1952.v The photographic and other hardenable layers of a photographic element used in the practice of the invention can be hardened by various organic or inorganic hardeners alone or in combination, such as aldehyde hardenersand blocked aldehydes, ketones, carboxylic and carbonic acid derivatives, sulfonate esters, sulfonyl halides and vinyl sulfones, active halogen compounds, epoxy compounds, azurindenes, active olefins, isocyanates, carbodiimides, mixed function hardeners and polymeric hardeners such as oxidized polysaccharides suchas dialdehyde starch and oxyguargum and the like.

A photographic element and emulsions described in the practice of the invention can contain various colloids alone or in combination as vehicles, binding agents and in various layers. Suitable hydrophilic materials include those naturally-occurring substances such as proteins, for

example, gelatin, gelatin derivatives, cellulose derivatives,

polysaccharides such as dextran, gum arabic and the like; and synthetic polymeric substances such as water-soluble polyvinyl compounds like poly(vinylpyrrolidone), acrylamide polymers and the like.

The described photographic emulsion layers and other layers of the photographic element employed in the practice of the invention can also contain, alone or in combination with hydrophilic, water-permeable colloids, other synthetic polymeric compounds such as dispersed vinyl compounds, such as in latex form, and particularly those which increase the dimensional stability of the photographic, materials. Suitable synthetic polymers include those described in U.S. Pat. 3,142,586 of Nottorf issued July 28, 1964; U.S. Pat. 3,193,386 of White issued July 6, 1965; U.S. Pat. 3,062,674 of Houck et al., issued Nov. 6, 1962; U.S. Pat. 3,220,844 of Houck et al. issued Nov. 30, 1965; U.S. Pat. 3,287,289 of Ream et al. issued Nov. 22, 1966 and U.S. Pat. 3,411,911 of Dykstra issued Nov. 19, 1968. Particularly efiective are those water-insoluble polymers of alkyl acrylates and methacrylates, acrylic acid, sulfoalkyl acrylates or methacrylates, and those which have crosslinking sites which facilitate hardening or curing as well as those having recurring sulf-obetaine units as described in Canadian Pat. 774,054.

The photographic elements employed in the practice of the invention can contain antistatic or conducting layers. Such layers can comprise soluble salts such as chloride, nitrate and the like evaporated metal layers, ionic polymers such as those described in U.S. Pat. 2,861,056 of Minsk issued Nov. 18, 1958 and U.S. Pat. 3,206,312 of Sterman et al. issued Sept. 14, 1965 or insoluble organic salts such as those described in U.S. Pat. 3,428,451 of Trevoy issued Feb. 18, 1969.

The photographic emulsions and other layers of a photographic element employed in the practice of the invention and described herein can be coated on a wide variety of supports. Typical supports include cellulose nitrate film, cellulose ester film, poly(vinylacetal) film, polystyrene film, poly(ethylene terephthalate) film, polycarbonate film and related films or resinous materials as well as glass,

paper, metal and the like. Typically a flexible support is employed, especially a paper support which can be partiallyacetylated or coated with baryta and/or an alpha olefin polymer, particularly a polymer of an alpha olefin containing 2 to 10 carbon atoms such as polyethylene, polypropylene, ethylene-butene copolymers and the like.

The' photographic elements employed in the practice ofthe invention can contain plasticizers and lubricants such as polyalcohols, glycerin and diols as described, for example, in U.S. Pat. 2,960,404 of Milton et al. issued Nov. 1, 1966; fatty acids or esters such as described in U.S. Pat. 2,588,765 of 'Robijns issued Mar. 11, 1952; and U.S. Pat. 3,121,160 of Duane issued'Feb. 11, 1964; and silicone resins such as those described in British Pat.

The photographic elements employed in the practice of the invention can contain surfactants such as saponin, anionic compounds, such as alkyl aryl sulfonates described, for example, in U.S. Pat. 2,600,831 of Baldsiefen issued June 17, 1952 and amphoteric compounds such as those descirbed in U.S. Pat; 3,133,816 of Ben-Ezra issued May 19, 1964.

The photographic elements employed in-the practice of the invention can contain matting agents such as starch, titanium dioxide, zinc oxide, silica, and polymeric beads including beads described, for example, in U.S. Pat. 2,992,- 101 of Jelley et al. issued July 11, 1961 and U.S. Pat. 2,701,245 of Lynn issued Feb. 1, 1955.

The described photographic elements employed in the practice of the invention can also contain brightening agents including stilbene, triazine, oxozole, and/or coumarin brightening agents. Water-soluble brighteners such as those described in German Pat. 972,067 and U.S. Pat. 2,933,390 of McFall et'al. issued Apr. 19, 1960 or dispersions of brighteners can be used such as those described in German Pat. 1,150,274 and U.S. Pat. 3,406,070 of Oetiker et al. issued Oct. 15, 1968 and French 1,530,244.

The photographic silver halide emplsions employed in the practice of the invention can be X-ray or other nonspectrally sensitized emulsions or they can contain spectral sensitizing dyes. The photographic silver halide emulsions can conveniently be ortho-sensitized or pan sensitized with spectral sensitizing dyes. For instance, these emulsions can be spectrally sensitized by treating with a solution of a sensitizing dye in an organic solvent or the dye can be added in the form of a dispersion such as described in French Pat. 1,482,774. Spectral sensitizing dyes useful in sensitizing such emulsions are described, for example, in U.S. Pat. 2,526,632 of Brooker et al. issued Oct. 24, 1950; U.S. Pat. 2,503,776 of Sprague issued Apr. 11, 1950; U.S. Pat. 2,493,748 of Brooker et al. issued Jan. 10, 1950; and U.S. Pat. 3,384,486 of Taber et al. issued May 21, 1968. Spectral sensitizers which can be used include the cyanines, merocyanines, complex (trinuclear or tetranuclear) cyanines, complex (trinuclear or tetranuclear) merocyanines, holopolar cyanines, styryls, hemicyanines, such as enamine hemicyanines, oxonols and hemioxonols. Dyes of the cyanine classes can contain such basic groups as the thiazolines, oxazolines, pyrrolines, pyridines, oxazoles, thiazoles, selenazoles and imidazoles. Such groups can contain alkyl, alkylene, hydroxyalkyl, sulfoalkyl, carboxyalkyl, aminoalkyl and enamine substituents and can be fused to carbocyclic or heterocyclic ring systems either unsubstituted or substituted with halogen, phenyl, alkyl, haloalkyl, cyano or alkoxy groups. The dyes can be symmetrical or unsymmetrical and can contain alkyl, phenyl, enamine or heterocyclic substituents on the methine or polymethine chain. The merocyanine dyes can contain the basic groups described as well as acid groups such as thiohydantoins, rhodanines, oxazolidenediones, thiazolidenediones, barbituric acids, thiazolineones and malononitrile. These acid groups can be substituted with alkyl, alkylene, phenyl, carboxyalkyl, sulfoalkyl, hydroxyalkyl, alkoxyalkyl, alkylamino groups or heterocyclic groups. Combinations of these dyes can be used if desired. In addition, supersensitizing addenda which do not absorb visible light can be included, such as ascorbic acid derivatives, azaindenes, cadmium salts and organic sulfonic acids as described in U.S. Pat. 2,933,390 of McFall et al. issued Apr. 19, 1960 and U.S. Pat. 2,937,089 of Jones et al. issued May 17, 1960.

The various layers including the photographic emulsion layer of the photographic element employed in the practice of the invention can contain light absorbing materials and filter dyes such as those described in U.S. Pat. 3,253,- 921 of Sawdey issued May 31, 1966; U.S. Pat. 2,274,782 of Gaspar issued Mar. 3, 1942; U.S. Pat. 2,527,583 of Silberstein et al. issued Oct. 31, 1950 and U.S. Pat. 2,956,- 879 of VanCampen issued Oct. 18, 1960. If desired, the dyes can be mordanted, for example, as described in U.S. Pat. 3,282,699 of Jones et al. issued Nov. 1, 1966.

The sensitizing dyes and other addenda such as the described silver halide developing agent precursors used in the practice of the invention can be added from water solutions or suitable organic solvent solutions can be used. The compounds can be added using various procedures including those described in U.S. Pat. 2,912,343 of Collins et al. issued Nov. 10, 1959; U.S. 3,342,605 of McCrossen et al. issued Sept. '19, 1967; U.S. Pat. 2,996,- 287 of Audran issued Apr. 15, 1961 and U.S. Pat. 3,425,- 835 of Johnson et al. issued Feb. 4, 1969.

The described esters can be employed in combination with a so-called stabilizer precursor. These are typically a sulfur-containing compound, contiguous to photographic silver halide, which in the presence of an activator, breaks down or cleaves to form a compound that combines or complexes with the silver halide in unexposed and undeveloped areas of a photographic element to form a complex or compound which is believed to be silver mercaptide, which is more stable than silver halide to light, humidity, and ambient conditions. Such compounds are described, for example, in U.S. Pat. 3,301,678 of Huinphlett et al. issued Jan. 31, 1967 and Belgian 709,967 as well as Belgian Pat. 709,900. Examples of suitable silver halide stabilizer precursors useful in the practice of the invention include:

3-S- N,N,N, N -tetramethylisothiuronium) propane sulfonate,

3-S-isothiuronium propane sulfonate,

2-S-isothiuronium ethane sulfonate,

3-S-(N,N'-dimethyl-N,N'-ethylene)isothiuronium propane sulfonate,

S- 2-meth'ylsulfinylethyl) isothiuronium trifluoroacetate,

and/or 2-(3-S-sulfopropyl)mercapto-S-(2-hydroxyethyl)- '1,4,5,6-tetrahydro-1,3,5-triazine.

A suitable concentration of stabilizer precursor will vary depending upon the particular photographic element, the desired image, the processing conditions and the like. Usually a concentration of about 0.25 to about 10 moles of stabilizer precursor per mole of photographic silver halide in the element is suitable.

Another embodiment of the invention is a photographic composition comprising a photographic compound, e.g. photographic silver halide, and an amino reductone ester silver halide developing agent precursor, as described. This photographic composition can be, for example, a. photographic silver halide gelatino emulsion.

After exposure, the resulting latent image in a photographic element containing the described ester silver halide developing agent precursor can be developed by contacting the element with an alkaline development activator. An especially suitable activator is an aqueous alkaline solution comprising an alkali metal hydroxide at a pH of about 10 to about 14.5, especially 12 to 14.5.

Alkaline activators which can be employed in developing a latent image in a photographic element as described include any of those which provide the desired activation of the described silver halide developing agent precursor. These include, for instance, aqueous alkaline activator solutions commonly employed in rapid access processing of photographic elements, such as those employed in socalled reader-printers. Alkaline activators which are suitable include inorganic alkali such as alkali metal hydroxides, especially sodium hydroxide, potassium hydroxide and/or lithium hydroxide, alkali metal carbonates, such as sodium carbonate and potassium carbonate, sodium or potassium phosphates, and organic alkaline development activators such as quaternary ammonium bases and salts and alkanolamines such as ethanol amine, and similar alkaline materials and/or alkali releasing materials. Such development activators can be applied to the photographic element employed in the practice of the invention in any suitable manner, including for example, dipping, spraying and/or surface application such as with rollers, as described in U.S. Pat. 3,025,779 of Russell et al. issued Mar. 20, 1962 or by surface application processing as described in U.S. Pat. 3,418,132 of Kitze issued Dec. 24, 1968.

If desired an alkaline solution can be employed containing conventional silver halide developing agents, such as those described. So-called web processing can be employed as described, for example, in U.S. Pat. 3,179,517 of Tregillus et al. issued Apr. 20, 1965 or so-called stabilization processing as described in Russell et al., PSA Journal, volume 1617, August 1950.

If desired the alkaline activator, especially an aqueous alkaline activator solution can contain a hardener as described.

The time for processing a photographic element in the practice of the invention, that is developing and stabilizing a desired latent image, can vary over a wide range, typically between about 1 second to several minutes depending on the desired image, processing conditions and the like.

The conditions for processing can also vary, but usually ambient pressures and temperatures of about 20 C. to about 30 C. are employed. If desired, higher temperatures can be used such as temperatures up to about 90 C.

It can be useful in some cases to wash the resulting photographic element after processing with water, such as a water rinse, for about 1 second to about 5 seconds to remove water-soluble compounds. This can improve post-processinng stability and reduce any stain.

The described ester silver halide developing agent precursors can be employed in a range of photographic silver halide processing compositions, e.g. in photographic silver halide developer compositions, hardener compositions, monobaths, and the like. Accordingly, another embodiment of the invention is: in a photographic silver halide processing composition comprising an alkaline development activator and a photographic silver halide developing agent precursor the improvement comprises an amino reductone ester silver halide developing agent precursor, as described.

The photographic silver halide processing composition can comprise a silver halide solvent. Typical silver halide solvents include, for example, alkali metal or ammonium thiosulfates and thiocyanates, such as sodium thiosulfate, sodium thiocyanate or ammonium thiocyanate.

The processing composition, as described, can be a monobath. Typical components of monobaths aredescribed, for example, in the Monobath Manual, by Grant M. Haist, published by London Press, 1966. 1

The described silver halide developing agent precursors can be employed in a diffusion transfer photographic system, especially a photographic silver salt diffusion transfer photographic system. They can be employed in one or more layers of a photographic element and/ or in a processing composiiton in such a system, if desired. Suitable diffusion transfer systems, processes, processing compositions and elements therefor are described, for example in U.S. Pat. 2,452,181 of Land issued Feb. 27, 1951 and- U.S. Pat. 3,337,342 of Green issued Aug. 27, 1967. They can be used in so-called high speed diflusion transfer systems, processes and compositions therefor, as described, for example, in U.S. Pat. 3,326,683 of Land et a1. issued June 20, 1967; or in other types of diffusion transfer systems, such as described in U.S. Pat. 2,857,274 of Land et a1. issued Oct. 21, 1-958; U.S. Pat. 3,020,155 of Yackel issued Feb. 6, 1962; U.S. Pat. 2,584,030 of Land issued Jan. 29, 1952 and U.S. Pat. 2,923,623 of Land issued Feb. 2, 1960. An especially suitable diffusion transfer system is set out in copending U.S. application Ser. No. 863,363 of Youngquist, filed Oct. 2, 1969. These references describe typical photographic products suitable for diffusion transfer systems, comprising in combination (a) a photographic element comprising photographic silver halide (b) a processing composition containing a silver halide solvent, typically in a rupturable container, and (c) an image receiving layer. Accordingly, another embodiment of the invention comprises in a photographic product comprising in combination (a) a photographic element comprising photographic silver halide, (b) a processing composition containing a silver halide solvent, and (c) an image receiving layer, the improvement comprising an amino reductone ester silver halide developing agent, precursor, as described. The amino reductone ester silver halide developing agent precursor is preferably present in the processing composition and/ or image receiver.

The developing agent precursors employed in the practice of the invention can be present in one or more layers of elements designed for color photography, for example,

elements containing color-forming couplers, or elements 10 to be developed in solutions containing color-forming couplers; or in so-called false-sensitized color materials, such as those described in Hausar U.S. Pat. 2,763,549.

The developing agents employed in the practice of the invention can be used in elements designed for physical development such as those described in British Pat. 920,277 and British Pat. 1,131,238.

If desired, the described developing agent precursors can be employed in so-called hardening developers such as described in U.S. Pat. 3,232,761 of Allen and Burness issued Feb. 1, 1966; or-in roller transport processors, such as described in U.S. Pat. 3,025,779 of Russell et al., issued Mar. 20, 1962.

The described developing agent precursors can also be employed in elements designed for so-called dry processing with heat, such as described in U.S. Pat. 3,152,904 of Sorensen et al. issued Oct. 13, 1964; U.S. Pat. 3,457,075 of Morgan et al. issued July 22, 1969; US. Pat. 3,312,550 of Stewart et al. issued Apr. 4, 1967 and U.S. Pat. 3,418,122 of Colt issued Dec. 24, 1968.

Accordingly, another embodiment of the invention is: in a photographic process comprising developing a latent image in an exposed photographic silver halide element employing a silver halide developing agent precursor which is contacted with an alkaline development activator, the improvement comprising employing as said developing agent precursor an amino reductone ester silver halide developing agent precursor, as described.

This, can be, for example, in a photographic process comprising developing a latent image in an exposed pho tographic element, containing a silver halide developing agent precursor and photographic silver halide, by contacting the element with an alkaline development activator, the improvement wherein the silver halide developing agent precursor is an amino reductone ester silver halide developing agent precursor, as described.

-Or, it can be, for example, in a photographic diffusion transfer process comprising developing a latent image in a photographic diffusion transfer product comprising (a) a photographic element comprising photographic silver halide, (b) a processing composition comprising a silver halide solvent, and (c) an image receiving layer the improvement comprising employing an amino reductone ester siler halide developing agent precursor, as described. More particularly, this can, for example, comprise the steps of exposing a photographic silver halide layer to form a latent image therein; developing the latent image with a processing composition, eg at a pH of about 12 to about 14, comprising a reductone ester silver halide developing agent, as described; contacting undeveloped silver halide in the photographic silver halide layer with a silver halide solvent to form an imagewise distribution of a silver complex in the unexposed areas of the photographic silver halide layer; transferring at least part of the silver complex to an image receiver layer contiguous to the photographic silver halide layer; reducing the silver complex in the presence of development nuclei to form a visible image in the receiver layer; and lowering the pH of the processing composition to below about 8 to form a stable developed image.

The photographic elements employed in the described diffusion transfer system are especially suitable containing a silver halide developing agent, as described. Aminoalkylhydroquinone silver halide developing agents, such as 2-methyl-5-mo rpholinomethyl hydroquinon e, Z-methyl-5-pyrr0lidin0methyl hydroquinone, or 2-methyl-5-piperidinomethyl hydroquinone provide good results in a photographic element, as described.

The following examples are included for a further understanding of the invention.

11 EXAMPLE 1 This illustrates the invention.

An aqueous alkaline silver halide developer solution is prepared containing per liter of water 0.2 mole of sodium sulfite, 0.02 mole of piperidino hexose reductone monoacetate and sufiicient sodium hydroxide to adjust the pH of the solution to 12.5. This converts the described precursr to developing agent form and provides a silver halide developer solution.

A photographic film containing a fine grain silver bromoiodide gelatino emulsion is sensitometrically exposed through a step wedge. The resulting film is immersed under ambient conditions in the described developer solution until a density of 2.0 is developed in the fourth step of the exposed portion of the film. This requires 2.7 minutes.

EXAMPLE 2 This is a comparative example.

The procedure set out in Example 1 is repeated with the exception that hydroquinone is employed in place of piperidino hexose reductone monoacetate.

The time required to develop an image density of 2.0 is 3.4 minutes. This demonstrates that a silver halide developing agent precursor and the solution provided in Example 1 is significantly more active than hydroquinone, a well-known silver halide developing agent.

EXAMPLE 3 The procedure set out in Example 1 is repeated with the exception that sodium phosphate, instead of sodium hydroxide, is employed in the described silver halide developer solution to provide a pH of 11.5.

The time required to develop an image density of 2.0 is 3.2 minutes.

EXAMPLE 4 This is a comparative example.

Piperidino hexose reductone is added to 1 liter of water at 21 C. until no more piperidino hexose reductone dissolves. The solution is saturated when less than 0.01 molar piperidino hexose reductone is reached.

The test is repeated employing piperidino hexose reductone monoacetate. -In excess of 0.10 molar piperidino hexose reductone monoacetate is soluble in water, i.e. an increase in solubility of over 10 times.

EXAMPLE 5 This is a comparative example.

The procedure set out in Example 4 is repeated with the exception that an aqueous solution of 0.2 molar sodium sulfite and 0.2 molar sodium carbonate at a pH of 10.0 is employed in place of water.

A concentration of less than 0.02 molar piperidino hexose reductone is dissolved with great difiiculty in this solution, while a concentration of 0.04 molar piperidino hexose reductone monoacetate is soluble in the described alkaline solution.

This increase in solubility is surprising since esterified hydroquinone compounds, such as 1,4-bis(chloroacetoxy) benzene, as described in US. Pat. 3,246,988 of Porter et al. issued Apr. 19, 1966, are much less soluble in aqueous solution or aqueous alkaline solutions than the parent hydroxy benzene compounds.

EXAMPLE 6 This is a comparative example.

0.211 gram (0.0012 mole) of piperidino hexose reductone is mixed in 16 milliliters of a silver chloride gelatino emulsion containing 0.004 mole of silver chloride and 8.5 percent by weight pigskin gelatin, the pH of which is adjusted to 3.0 with sulfuric acid. The resulting photographic emulsion is coated on a white pigmented film support at a silver coverage of about 35 mg. of emulsion per 929 square centimeters of support. The piperidino 12 hexose reductone does not completely dissolve in the emulsion, resulting in a rough coating.

EXAMPLE 7 The procedure set out in Example 6 is repeated with the exception that 0.253 gram (0.0012 mole) of piperidino hexose reductone monoacetate is employed in place of piperidino hexose reductone.

The resulting emulsion coating is smooth, not rough as in Example 6. This indicates the piperidino hexose reductone monoacetate is significantly more soluble in an emulsion, as described, than the unacetylated piperidino hexose reductone.

EXAMPLE 8 The photographic element which is prepared as described in Example 7 is sensitometrically exposed through a step wedge to tungsten light. The resulting latent image is then developed by immersing the photographic element in an aqueous alkaline development activator solution at 21 C. containing 25.0 grams of sodium carbonate monohydrate, and 25.0 grams of anhydrous sodium sulfite in one liter of water with sufficient acetic acid added to adjust the pH of the solution to 10.0. The photographic element is immersed in the activator solution for 40 seconds.

The resulting image is then fixed in Kodak F-5 Fixer for 5 seconds and washed with water.

The developed image has good density, no visible fog, and has a uniform appearance.

EXAMPLE 9 This is a comparative example.

The procedure set out in Example 8 is repeated with the exception that a photographic element as described in Example 6 containing piperidino hexose reductone is employed in place of a photographic element containing piperidino hexose reductone monoacetate.

The resulting developed image has significantly lower density and less uniform appearance than the image developed as described in Example 8.

EXAMPLE 10 A photographic element is prepared as described in Example 7. It is sensitometrically exposed to tungsten light through a step wedge and then suspended for 3 minutes at 21 C. in a closed container over an aqueous ammonium hydroxide solution containing 28% by volume ammonium hydroxide. This provides activation of the acetate silver halide developing agent precursor with ammonia. The resulting developed image is fixed in Kodak F-S Fixer for 5 seconds and washed with water.

The developed image has good density and uniform appearance.

EXAMPLES 11-30 Similar results to those set out in Example 8 are obtained employing the following ester silver halide de veloping agent precursors in place of piperidino hexose reductone monoacetate:

EXAMPLE 11 Morpholino hexose reductone monoacetate.

EXAMPLE 12 Pyrrolidino hexose reductone monoacetate.

EXAMPLE 13 Dimethylmorpholino hexose reductone monoacetate.

EXAMPLE 14 Methylpiperidino hexose reductone monoacetate.

EXAMPLE 15 N-benzyl-N-methylamino hexose reductone monoacetate.

EXAMPLE 16 Dimethylamino hexose reductone monoacetate.

EXAMPLE 17 Anhydro morpholino hexose reductone acetate.

p EXAMPLE 1s Anhydrozpyrrolidino hexose reductone acetate.

' EXAMPLE 19 v Anhydro dimethylmorpholino hexose reductone acetate.

7 EXAMPLE 20' p A Anhydro methylpiperidino hexose reductone acetate.

EXAMPLE 21 Anhydro dimethylamino hexose reductone acetate.

EXAMPLE 22 Anhydro dihydro morpholinohexose reductone acetate.

- EXAMPLE 23 Anhydro dihydro pyrrolidino hexose reductone acetate.

EXAMPLE 24 Anhydro piperidino hexose reductone acetate.

EXAMPLE 25 Anhydro dihydro piperidino hexose reductone acetate.

EXAMPLE 26 Anhydro dihydro methylpiperidino hexose reductone acetate.

Anhydro dihydro piperidino hexose reductone methyl sulfonate. EXAMPLE 31 A This illustrates a diffusion transfer system. L A j A processing composition is prepared by' fnixing the following components: G

Sodium sulfite 60.0 Sodium thiosulfate pentahydrate 40.0 Sodium iodide L 1.5 Sodium'hydroxide -L 64.0 Hydroxyethyl cellulose (sold under the trade name 'Natrasol 2501-1 by Hercules Powder Company,

' U.S.A.) 25.0

Piperidino hexose reductone monoacetate 5.0 Water to 1 liter. 1

The resulting processing solution is a viscous liquid.

A photographic element is prepared by coating a gelatin solution containing a silver halide developing agent, which is 2-methyl-5-morpholinomethyl hydroquinone on electron bombarded polyethylene coated paper at about 240 mg. of gelatin per square foot and at 50 mg. of developing agent per square foot. Over this layer is coated a coarse grain silver bromoiodide gelatino emulsion containing mole percent iodide and a concentration of 125 mg. of silver per square footand 320 mg. of gelatin per 929 square centimeters of support. An image receiver is prepared by coating a water resistant paper support with palladium development nuclei dispersed in a polymeric binder.---- A 1 The described photographic element is sensitometrically exposed. The processing composition, as described, is then squeezed between the photographic element and the image receiver and the resulting so-called sandwich is squeezed between two rollers. After 20 seconds the so-called sandwich is pulled apart and the resulting image on the image receiver is observed.

The resulting developed image on the receiver has a maximum reflection density of 1.44 and has relatively little stain.

Alternatively the developing agent precursor can be incorporated in the receiver. Amounts of about 500 mg. per 929 square centimeters of support of the reductone esters can be incorporated in the polymeric binder of the receiver.

Development nuclei or silver precipitating agents which can be employed in diffusion transfer systems, as described can be physical development nuclei or chemical precipitants including, for example: (a) heavy metals in colloidal form and salts of these metals, (b) salts of amines which form silver salts and/or (c) nondiffusing polymeric materials with functional groups capable of combining with silver amines. Suitable development nuclei and/or silver image precipitating agents within the described classes include metal sulfides, selenides, polysulfides, polyselenides, thiourea and its derivatives, stannous halides, sulfur, gold, platinum, palladium, and mercury, colloidal sulfur, aminoguanidine sulfate, aminoguanidine carbonate, arsenous oxide, sodium stannite, hydrazines, xanthates, and similar agents disclosed, for example, in US. 'Pat. 3,020,- 155 of Yackel et al. issued Feb. 6, 1962. A nondilfusing polymeric silver precipitant or development nuclei, such as poly(vinylmercaptoacetate) can also be employed.

A wide range of concentrations of development nuclei of silver precipitating agents can be employed. A concentration of the development nuclei or silver precipitate in the image receiving layer must be at least sufficient to insure the development of a positive image and sufiicient removal of undeveloped silver salt from the light-sensitive layer to be processed.

A processing composition employed in a diffusion transfer system, as described, is typically a viscous processing composition. A wide range of viscosity can be employed. The viscosity can be about 20 to about 100,000

centipoises, typically about to about 10,000. Various thickening agents are suitable in the described processing compositions and processes of the invention. Any of those commonly employed in diffusion transfer photographic systems can be employed, as well as those employed in viscous monobaths. These include those described, for example, in U.S.-Pat. 3,120,795 of Land issued Feb. 11, 1964, e.g. hydroxyethyl cellulose and carboxymethyl cellulose.

The described photographicelement, receiving element and/or processing composition can also contain toning agents. Typical toning agents which can be employed include, for example, polyvalent inorganic salts as described in US. Pat. 2,698,236 of Land issued Dec. 28, 1954; silica as described in US. Pat. 2,698,237 of Land issued Dec. 28, 1954; and heterocyclic mercaptans such as mercaptozoles, e.g. mercaptodiazoles, mercaptotriazoles, mercaptotetrazoles, and the corresponding selenoazoles.

The photographic elements, processing compositions and/or image receivers employed in the practice of the invention can contain antioxidants, such as aldehyde-bisulfite condensation products, e.g. sodium formaldehydebisulfite.

Also the image receiver can contain an acid, especially a polymeric acid, which can provide lower pH in the image receiver after processing.

The invention has been described in detail with particular reference to preferred embodiments thereof, but it will be understood that variations and modifications 15 can be effected within the spirit and scope of the invention.

What is claimed is:

1. A photographic element comprising a support, photographic silver halide and an amino reductone ester silver halide developing agent precursor having the formula:

where R, and R are each hydrogen, alkyl containing 1 to 20 carbon atoms or atoms which with the nitrogen atom complete a 5 or 6 member saturated heterocyclic ring; 3 is or SO -R wherein R is hydrogen, alkyl containing 1 to 20 carbon atoms, aryl containing 6 to 12 carbon atoms, amino, or a or 6 member heterocyclic group; n is a positive integer of 1 to 2; R and R are each hydrogen, hydroxy, or alkyl containing 1 to 5 carbon atoms.

2. A photographic element as in claim 1 wherein said amino reductone ester silver halide agent precursor is piperidino hexose reductone monoacetate.

3. A photographic composition comprising photographic silver halide and an amino reductone ester silver halide developing agent precursor having the formula:

Where R and R are each hydrogen, alkyl containing 1 to 20 carbon atoms or atoms which with the nitrogen atom complete a 5 or 6 member saturated heterocyclic ring; R is or --SO R wherein R is hydrogen, alkyl containing 1 to 20 carbon atoms, aryl containing 6 to 12 carbon atoms, amino, or a 5 or 6 member heterocyclic group; n is a positive integer of 1 to 2; R and R are each hydrogen, hydroxy, or alkyl containing 1 to 5 carbon atoms.

4. A photographic composition as in claim 3 comprising a photographic silver halide gelatino emulsion.

5. A photographic composition as in claim 3 wherein said amino reductone ester silver halide developing agent precursor is piperidino hexose reductone monoacetate.

6. In a photographic silver halide processing composition comprising an alkaline development activator and a photographic silver halide developing agent precursor the improvement comprising an amino reductone'ester silver halide developing agent precursor having the formula:

16 atom complete a 5 or 6 member saturated heterocyclic ring; R is or SO -R wherein R is hydrogen, alkyl containing 1 to 20 carbon atoms, aryl containing 6 to 12 carbon atoms, amino, or a 5 or 6 member heterocyclic group; n is a positive integer of 1 to 2; R and R are each hydrogen, hydroxy, or alkyl containing 1 to 5 carbon atoms.

7. A photographic silver halide processing composition as in claim 6 wherein said amino reductone ester silver halide developing agent precursor is piperidino hexose reductone monoacetate.

8. A photographic silver halide processing composition as in claim 6 comprising a silver halide solvent.

9. A photographic silver halide processing composition as in claim 6 comprising a monobath.

10. In a photographic diffusion transfer product comprising in combination (a) a photographic element comprising photographic silver halide, (b) a processing composition comprising a silver halide solvent, and (c) an image receiving layer, the improvement comprising an amino reductone ester silver halide developing agent precursor having the formula:

where R and R are each hydrogen, alkyl containing 1 to 20 carbon atoms or atoms which with the nitrogen atom complete a 5 or 6 member saturated heterocyclic ring; R;, is

or -SO -R wherein R is hydrogen, alkyl containing 1 to 20 carbon atoms, aryl containing 6 to 12 carbon atoms, amino, or a 5 or 6 member heterocyclic group; n is a positive integer of 1 to 2; R and R are each hydrogen, hydroxy, or alkyl containing 1 to 5 carbon atoms.

11. A photographic diffusion transfer product as in claim 10 wherein said processing composition is present in a rupturable container and said amino reductone ester silver halide developing agent precursor is present in said processing composition.

12. A photographic diffusion transfer product as in claim 10 wherein said amino reductone ester developing agent precursor is present in said receiving layer.

13. In a photographic process comprising developing a latent image in an exposed photographic silver halide element employing a silver halide developing agent percursor which is contacted with an alkaline development activator the improvement comprising employing as said silver halide developing agent precursor an amino reductone ester silver halide developing agent precursor having the formula:

where R and R are each hydrogen, alkyl containing 1 to 20 carbon atoms or atoms which with the nitrogen atom complete a or 6 member saturated heterocyclic ring; R3 iS or -SO R wherein R is hydrogen, alkyl containing 1 to 20 carbon atoms, aryl containing 6 to 12 carbon atoms, amino, or a 5 or 6 member heterocyclic group; n is a positive integer of 1 to 2; R and R are each hydrogen, hydroxy, or alkyl containing 1 to 5 carbon atoms.

14. A photographic process as in claim 13 wherein said amino reductone ester silver halide developing agent precursor is piperidino hexose reductone monoacetate.

15. In a photographic process comprising developing a latent image in an exposed photographic element, containing a silver halide developing agent precursor and photographic silver halide, by contacting said element with an alkaline development activator, the improvement wherein said silver halide developing agent precursor comprises an amino reductone ester silver halide developing agent precursor having the formula:

where R and R are each hydrogen, alkyl containing 1 to 20 carbon atoms or atoms which with the nitrogen atom complete a 5 or 6 member saturated heterocyclic ring; R3 is or SO -R wherein R is hydrogen, alkyl containing 1 to 20 carbon atoms, aryl containing 6 to 12 carbon atoms, amino, or a 5 or 6 member heterocyclic group; n is a positive integer of 1 to 2; R and R are each hydrogen, hydroxy, or alkyl containing 1 to 5 carbon atoms.

16. In a photographic difiusion transfer process comprising developing a latent image in a photographic diffusion transfer product comprising (a) a photographic element comprising photographic silver halide, (b) a processing composition comprising a silver halide solvent, and (c) an image receiving layer the improvement comprising employing an amino reductone ester silver halide developing agent precursor having the formula:

where R, and R are each hydrogen, alkyl containing 1 to 20 carbon atoms or atoms which with the nitrogen atom complete a 5 or 6 member saturated heterocyclic ring; R is or SO -R wherein R is hydrogen, alkyl containing 1 to 20 carbon atoms, aryl containing 6 to 12 carbon atoms, amino, or a 5 or 6 member heterocyclic group; n is a positive integer of 1 to 2; R and R are each hydrogen, hydroxy, or alkyl containing 1 to 5 carbon atoms.

17. A photographic diifusion transfer process as in claim 16 wherein said amino reductone ester is piperidino hexose reductone monoacetate.

18. A photographic process which comprises the steps of exposing a photographic element comprising a photographic silver halide layer to form a latent image therein: developing said latent image with a processing composition comprising an amino reductone ester silver halide developing agent precursor having the formula:

Rs R5 where R; and R are each hydrogen, alkyl containing 1 to 20 carbon atoms or atoms which with the nitrogen atom complete a 5 or 6 member saturated heterocyclic ring; R3 is or SO R wherein R is hydrogen, alkyl containing 1 to 20 carbon atoms, aryl containing 6 to 12 carbon atoms, amino, or a 5 or 6 member heterocyclic group; n is a positive integer of 1 to 2; R and R are each hydrogen, hydroxyl, or alkyl, containing 1 to 5 carbon atoms; contacting undeveloped silver halide in the photographic silver halide layer with a silver halide solvent to form an imagewise distribution of a silvercomplex in the unexposed areas of the photographic silver salt layer; transferring at least part of the silver complex to an image receiver layer contiguous to the photographic silver salt layer; reducing the silver complex in the presence of development nuclei to form a visible image in the receiver layer; and lowering the pH of the processing composition to below about 8 to form a stable developed image.

19. A photographic process comprising developing a latent image in an exposed photographic element containing a silver halide developing agent precursor and photographic silver halide by contacting said element with ammonia, the improvement wherein said silver halide developing agent precursor comprises an amino reductone Ru R5 wherein R and R are each hydrogen, alkyl containing 1 to 20 carbon atoms or atoms which with the nitrogen atom complete a 5 or 6 member saturated heterocyclic ring; R, is

or -SO R wherein R is hydrogen, alkyl containing 1 to 20 carbon atoms, aryl containing 6 to 12 carbon atoms, amino, or a 5 or 6 member heterocyclic group; n is a positive integer of 1 to 2; R and R are each hydrogen, hydroxy, or alkyl containing 1 to 5 carbon atoms.

20. A photographic process as in claim 19 wherein said amino reductone ester silver halide developing agent precursor is piperidino hexose reductone monoacetate.

References Cited UNITED STATES PATENTS 3,347,671 10/1967 Salminen 96-3 2,936,308 5/1960 Hodge 96--66.4

NORMAN G. TORCHIN, Primary Examiner E. C. KIMLIN, Assistant Examiner US. Cl. X.R. 96-3, 66.4 

